1. Field of the Invention
The present invention is directed to coating compositions comprising mechanochromic crystals that change color upon application of a load to the coating composition.
2. Description of Related Art
Polymeric materials are often used to coat various structural components in many industries, such as aerospace components, medical devices, turbines (as used in wind energy and generation and in manufacturing), and the like. These components may become damaged or stressed during use. Oftentimes, the damage or stress to an underlying structural component is not clearly visible. The structural components and the polymeric coating on these components are subjected to a variety of forces that impart elongation, compression, and shear stresses. These forces hasten the fatigue within the component and increase the risk of catastrophic failure of the component. Therefore, these components are routinely examined for structural integrity using visual and non-visual techniques, particularly when a sudden failure presents risk to equipment or human safety. This practice consumes valuable time and resources, and hidden dangers are often difficult or impossible to detect. Thus, catastrophic failures can occur within such components with little or no warning.
The ability to detect damage as it occurs and locate the area of damage would be helpful. In particular, materials that self-report the state of damage and stress applied thereto are helpful in eliminating or minimizing the failure of the underlying structural component.